- Cryptography: PKI, HSM, Symmetric and Asymmetric, ECDSA, TLS, AES, etc - SQL: PostgreSQL, MySQL, SQLite, H2 and many others - NoSQL: Aerospike, Mnesia, Memcached, Redis, Tarantool, Mongodb, LevelDB, bdb, groupcache, Cassandra, ScilaDB, etc - Polyglot: Go, Python3, Lua, C, Rust, Erlang, Elixir, Haskell, Lisp, OCaml, Perl, Solidity, C++ - Blockchain: Ethereum, Hyperledger, Exonum, BFT - Infosec: blackbox testing, fuzzing, whitebox analyze, owasp